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Agglomerated zeolite adsorbents, process for their preparation, and their use for adsorbing paraxylene from aromatic C8 fractions

a technology of agglomerated zeolite and paraxylene, which is applied in the field of agglomerated zeolite adsorbents, process for their preparation, and their use for adsorbing paraxylene from aromatic c8 fractions, can solve the problems that the skilled person in the art does not have a simple and reliable criterion for predicting their behaviour, and achieves the effect of improving the efficiency of these adsorben

Inactive Publication Date: 2002-06-25
INST FR DU PETROLE +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The term agglomeration is understood to refer to the production of solid particles from a mixture of zeolite(s) and binder(s) using any technique known to those skilled in the art, such as extrusion, granulation, compacting or spraying. The practical content of binder in the agglomerate generally does not exceed 30%, and preferably 20%, of the total mass of the adsorbent. The efficiency of these adsorbents is improved substantially by selecting a clay of the kaolin family as agglomeration binder, in practice kaolinite or halloysite, and by subjecting the granules to zeolitization.

Problems solved by technology

In this matter, a person skilled in the art does not appear to have available any simple and sufficiently reliable criterion for predicting their behaviour.

Method used

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  • Agglomerated zeolite adsorbents, process for their preparation, and their use for adsorbing paraxylene from aromatic C8 fractions

Examples

Experimental program
Comparison scheme
Effect test

example 1

Preparation of a Control Adsorbent

An industrial zeolite NaX, with an Si / Al ratio=1.25 and an Na / Al ratio=1, is agglomerated by intimately mixing 850 grams of zeolite X powder (expressed as calcined equivalent), 150 grams of Charentes kaolinite (expressed as calcined equivalent) and 6 grams of carboxymethylcellulose (retention adjuvant intended to retain the water during the extrusion operation) with the appropriate amount of water for the extrusion. The extrudate is dried, crushed so as to recover grains whose equivalent diameter is equal to 0.7 mm, and then calcined at 550.degree. C. under a stream of nitrogen for 2 hours. Its toluene-adsorbing capacity, determined at 25.degree. C. and under a partial pressure of 0.5, is 20.2%; this is interpreted as a micropore volume of 20.2 / 0.86=0.235 cm.sup.3 / g (in calculating the pore volume, it is considered that the density of the liquid phase is identical to the density of the adsorbed toluene, i.e. 0.86). This granule is exchanged using a...

example 2

Preparation of an Adsorbent According to the Invention

950 grams (calcined equivalent) of a zeolite X with an Si / Al ratio=1.01 obtained according to the process described in European Patent EP 0,486,384 or U.S. Pat. No. 5,173,462, are agglomerated with 170 grams (calcined equivalent) of Charentes kaolinite, 6 grams of carboxymethylcellulose and the appropriate amount of water to correctly extrude the paste obtained. The extrudates are then dried, after which they are calcined at a temperature of 600.degree. C. for 2 hours under a stream of dry nitrogen. They are then crushed in order to bring the equivalent diameter of the particles to 0.7 mm.

The crushed material thus obtained is subjected to the barium exchange treatment already described in Example 1 and is heat-activated at a temperature of 220.degree. C. The product thus obtained has a loss on ignition of 5% and a toluene-adsorbing capacity of 13% (0.15 cm.sup.3 / g micropore volume).

The adsorbent satisfies the selectivity test wi...

example 3

Preparation of an Adsorbent According to the Invention

As above, 950 grams of a zeolite X with an Si / Al ratio=1.01 are agglomerated with 170 grams of Charentes kaolinite, 6 grams of carboxymethylcellulose and the appropriate amount of water. The mixture is extruded. The extrudates are dried, calcined at a temperature of 600.degree. C. for 2 hours under a stream of dry nitrogen and are then crushed so as to bring their equivalent diameter to 0.7 mm.

10 grams of these agglomerates are then immersed in 17 ml of a 220 g / l sodium hydroxide solution for 3 hours at 95.degree. C. They are then washed four times with water.

In order to estimate the effectiveness of the zeolitization, a small portion of the product is heated to 550.degree. C. under a stream of dry nitrogen and a toluene-adsorbing capacity of 21.6% is determined. The overall active zeolite content is estimated at 95%, i.e. greater than its initial content in the agglomerated adsorbent.

The solid is then exchanged with barium under...

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Abstract

The present invention relates to agglomerated zeolite adsorbents based on faujasite with an Si / Al ratio such that 1<=Si / Al<=1.15, at least 70% exchanged with barium and optionally with potassium, and on a binder, preferably a zeolitizable binder.They are obtained by agglomerating zeolite powder with a binder, followed by exchange of the zeolite ions for barium ions and activation of the adsorbents thus exchanged.These adsorbents are particularly suitable for the adsorption of the para-xylene contained in aromatic C8 hydrocarbon fractions in the liquid phase, in processes of simulated fluid-bed type.

Description

The field of the invention is that of zeolite adsorbents for the separation of xylenes, in particular with a view to the industrial production of para-xylene.High-purity para-xylene is reclaimed industrially, inter alia, in order to be converted into terephthalic acid intended for the manufacture of PET.The prior art has recognized that adsorbents consisting of zeolites X or Y exchanged using ions such as barium, potassium or strontium, alone or as a mixture, are efficient at selectively adsorbing para-xylene in a mixture containing at least one other aromatic C.sub.8 isomer. U.S. Pat. Nos. 3,558,730, 3,558,732, 3,626,020 and 3,663,638 disclose adsorbents comprising aluminosilicates exchanged with barium and potassium, which efficiently separate para-xylene from a mixture of aromatic C.sub.8 isomers. These adsorbents are used as adsorption agents in liquid-phase processes, preferably of the simulated counter-current type similar to those described in U.S Pat. No. 2,985,589, which ar...

Claims

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Application Information

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IPC IPC(8): C07C7/13C07C7/00B01J20/18C07C15/08
CPCC07C7/13C07C15/08Y02P20/52B01J20/183B01J20/186B01J20/3085B01J20/3078Y02P20/50
Inventor PLEE, DOMINIQUEMETHIVIER, ALAIN
Owner INST FR DU PETROLE
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